From f316a2ed52195135a35e32d7096e876357c48c69 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Thu, 18 Sep 2014 20:03:23 +0000 Subject: initial commit: rc for execline-2.0.0.0 --- doc/redirfd.html | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 doc/redirfd.html (limited to 'doc/redirfd.html') diff --git a/doc/redirfd.html b/doc/redirfd.html new file mode 100644 index 0000000..fd29ef4 --- /dev/null +++ b/doc/redirfd.html @@ -0,0 +1,100 @@ + + + + + execline: the redirfd command + + + + + + +

+execline
+Software
+skarnet.org +

+ +

The `redirfd` program

+ +

+redirfd redirects a given file descriptor to a file, then +executes a program. +

+ +

Interface

+ +

+     redirfd [ -r | -w | -u | -a | -c | -x ] [ -n | -b ] fd file prog...
+

+ +

+redirfd redirects the file descriptor number fd +to file, then execs into prog.... +

+ +

Options

+ +

+ One and only one of the -r, -w, -u, -a, -c, or -x options must be given; +the -n and -b options may be added in any case. +

+ +

-r : open file for reading.
-w : open file for writing, truncating it if it already exists.
-u : open file for reading and writing.
-a : open file for appending, creating it if it doesn't exist.
-c : open file for appending. Do not create it if it doesn't exist.
-x : open file for writing, creating it, failing if it already exists.
-n : open file in non-blocking mode.
-b : change mode of file after opening it: +to non-blocking mode if the -n option was not given, +to blocking mode if it was.

+ +

Notes

+ +

redirfd -r n file prog... is roughly equivalent to +sh -c 'exec prog... n<file'
redirfd -w n file prog... is roughly equivalent to +sh -c 'exec prog... n>file'
redirfd -u n file prog... is roughly equivalent to +sh -c 'exec prog... n<>file'
redirfd -a n file prog... is roughly equivalent to +sh -c 'exec prog... n>>file'
redirfd -c n file prog... has no portable +shell equivalent. Some shells provide the noclobber option for +a similar feature.
redirfd -x n file prog... has no portable +shell equivalent.

+ +

Special fifo handling

+ +

+ The -n and -b options are especially useful with +named pipes. +

+ +

Opening a fifo for reading, blocking if there is no writer: +redirfd -r n fifo prog...
Opening a fifo for reading, with instant success even if +there is no writer, and blocking at the first attempt to read from it: +redirfd -r -nb n fifo prog...
Opening a fifo for writing, blocking if there is no reader: +redirfd -w n fifo prog...
Opening a fifo for writing, with instant success even if +there is no reader: +redirfd -w -nb n fifo prog.... Warning: +the first attempt to write to the fifo will raise a SIGPIPE if there is +still no reader at that time. The named pipe semantics normally do not +allow a fifo to be open for writing without a reading end, and you +should know what you are doing if you're using redirfd +this way.

+ + + -- cgit v1.2.3

The redirfd program

Interface

Options

Notes

Special fifo handling

The `redirfd` program